1. Field of the Invention
The present invention relates to a fuel injection system for an internal combustion engine having a plurality of cylinders. More particularly, the present invention relates to a fuel injection system having a plurality of fuel injectors and a fuel piping, having by a plurality of supply pipe members, which supplies fuel to the injectors.
2. Description of the Background Art
A number of fuel injection systems which supply fuel to plural fuel injectors of an internal combustion engine having a plurality of cylinders are known. An example of such fuel injection system for a vehicle engine, such as a motorcycle engine, is disclosed in the Japanese patent document JP-A No. H11-093802.
According to the Japanese patent document JP-A No. H11-093802, the fuel injection system for a motorcycle engine includes a plural fuel injectors and a fuel piping for supplying fuel to the plural injectors. The fuel piping includes a fuel introduction port for receiving fuel that is supplied (e.g., from a fuel tank via a fuel pump), a fuel path connecting the fuel introduction port, a plurality of injector connecting portions for connecting the injectors, and clamping parts for fixing the fuel piping to a vehicle component.
Generally, the fuel piping is integrally formed of an aluminum alloy or an extruded material, for example, as disclosed in JP-A No. H11-93802.
It is desirable that a fuel piping installed in a vehicle is of light weight. However, even with design changes, e.g. shape of fuel piping, there have been some constraints on reducing weight of the fuel piping which is generally made of a metallic material, such as aluminum alloy.
It is considered possible to reduce the weight of the fuel piping by manufacturing fuel piping using a light weight material, such as resin. However, integrally producing a long fuel piping made of a resin involves a moldability problem.
On the other hand, forming a long fuel piping by connecting shorter pipe members made of resin involves a functional problem. For example, the pipe members connected with each other may develop relative positional shifting between them, particularly at connecting portions, due to relatively rigid vehicle portions to which the fuel piping is attached.
In order to minimize relative positional shifting of the pipe members, the fuel pipings are generally formed of a metallic material resulting into heavy weight. Under such circumstances, fuel piping improvements are required in terms of both weight and cost. The present invention has been made in view of the above problem.
Accordingly, it is an object of the present invention to provide a fuel injection system which enables a reduction in weight of the system and improves manufacturability of required parts of the fuel injection system.